Vacuum Toilet System Indicates INOP on FAP

TASK 38-31-00-810-833-A
Vacuum Toilet System Indicates INOP on FAP

1. Possible Causes

membrane switch, WTR SYSTEM DEPRE
SENSOR,LEVEL [41MG]
Liquid Level Transmitter (LLT) REFERENCE LINE
XMTR-LEVEL [40MG]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 38-31-00-100-009	Cleaning of the Liquid Level Transmitter (LLT) Reference Line
AMM 38-31-00-710-009	Operational Test of the Toilet Unit
AMM 38-31-00-740-001	BITE Test of the Vacuum Toilet System
AMM 38-31-62-000-001	Removal of the Liquid Level Transmitter
AMM 38-31-62-400-001	Installation of the Liquid Level Transmitter
AMM 38-31-63-000-001	Removal of the Liquid Level Sensor
AMM 38-31-63-400-001	Installation of the Liquid Level Sensor
MCDU Display

3. Fault Confirmation
Subtask 38-31-00-710-160-A ** ON A/C NOT FOR ALL

A. Make sure that the light in the membrane switch, WTR SYSTEM DEPRE on the FAP is OFF.

Subtask 38-31-00-710-112-A ** ON A/C NOT FOR ALL

B. Fault Confirmation Test
(1) Make sure that the circuit breakers of the vacuum toilet system are closed.
(2) Do an operational test of the vacuum toilet system AMM 38-31-00-710-009.

4. Fault Isolation
Subtask 38-31-00-740-068-A ** ON A/C NOT FOR ALL

A. Do the bite test AMM 38-31-00-740-001.

Subtask 38-31-00-810-130-A ** ON A/C NOT FOR ALL

B. If the FAP gives the maintenance message SYSTEM INOP:

Refer to the LAST LEG REPORT or PREVIOUS LEGS REPORT page of the bite test.
MCDU Display ** ON A/C NOT FOR ALL

(1) If there is NO FAULTS indication on the LAST LEG REPORT or PREVIOUS LEGS REPORT page:

Operate the flush switches to flush the toilets.

(2) If the toilets do not flush:

open and close the circuit breaker 33MG.

(3) If the fault continues:

replace the SENSOR,LEVEL [41MG] , AMM 38-31-63-000-001 and AMM 38-31-63-400-001.
remove and clean the Liquid Level Transmitter (LLT) REFERENCE LINE, AMM 38-31-00-100-009.
replace the XMTR-LEVEL [40MG] , AMM 38-31-62-000-001 and AMM 38-31-62-400-001.

Subtask 38-31-00-710-113-A ** ON A/C NOT FOR ALL

C. Test
(1) Do the test as given in paragraph 3. A. to check the correct operation.
(2) After the subsequent flight, make sure that the fault does not continue.

[Rev.8 from Aug 2018] 2026.04.04 04:34:15 UTC